Modern Finite Element packages are capable of sophisticated nonlinear analyses of large structural systems, but the design of steel structures still relies heavily on the conventional member based design method. In conventional design, members of structural system, i.e. beams and columns are designed separately with equations that take into account the member forces and resistances.

Recently, a more holistic approach for structural design has been proposed in the literature, where the entire structure is treated as a system, whose load-carrying capacity is determined by advanced nonlinear analysis without separate member design checks. This so called direct design method (DDM) utilizes contemporary computational power and it exploits the full load-bearing capacity of steel structures. Compared to conventional design method, DDM is more sophisticated and it allows for more economical design of steel structures.

In this study, the DDM will be tailored for SSAB’s structural hollow sections with steel grades S355 up to S700 by using structural reliability theory. The aim of research is to develop a reliable and Eurocode compliant DDM that allows for the design of optimal structures in the perspective of overall economy. The developed design procedure allows more efficient use of steel in structures, thus improving the competitiveness of SSAB’s tubular products.